Understanding Round Trip Latency (RTL) in Live Events

”  Round Trip Latency (RTL) in live performance is the total time an audio signal travels from leaving the source (such as a microphone) to entering the mixer. Forward to external processing on the computer. and runs back and forth through the speakers or the musician's In-Ear Monitor headphones.
​    When a computer and a host program (Live Plugin Host / DAW) are used to insert live effects. The signal must travel through the Cumulative Latency Bottleneck through 5 main stages as follows:
Signal Loop Journey

1. A/D Conversion (Receiver Mixer):
   The microphone sends analog signals to the digital board. The signal is converted to digital data (0 and 1).
   Cumulative Latency: ~0.5 – 1.5 ms
   
2. Digital Audio Transport (send to computer):
   The digital signal is sent over a cable such as USB, Thunderbolt, or Audio Network protocol (Dante, SoundGrid, AVB) into the computer's Audio Driver (ASIO/CoreAudio).
   Cumulative latency: ~0.5 – 2 ms (depending on the type of connection)
   
3. Buffer Size & Host Processing (the heart of latency):
   Host programs (e.g. Ableton Live, Logic, MainStage, SuperRack) must first store data in a "hopper" or buffer in order to prevent the audio from jittering. (Dropouts/Glitches)
   Input Buffer: Wait for input queue (~1.5 – 3 ms)
   Processing: Signal routing software
   Output Buffer: Wait for data to be queued for output (~1.5 – 3 ms)
   (The lower the Buffer setting, such as 64 samples, the lower the latency but consumes a lot of CPU.)
   
4. Plugin Processing (latency from the plugin itself):
   Each plugin takes a different amount of time to calculate:
   Zero-Latency Plugins (EQ / Basic Comp): Does not increase latency (0 ms).
   Lookahead / Linear Phase / Pitch Correction: This group of plugins is required. "Eavesdropping" before working causes a huge increase in latency in the system.
   Cumulative latency: 0 ms to more than 15 ms each.
   
5. D/A Conversion & Return:
   The sound that passes through the plug-in flows from the computer back into the mixer, through the DSP system inside the board, and converted back into a real audio signal (Analog) and sent to the In-Ear Monitor or speaker cabinet.
   Cumulative Latency: ~1 – 2 ms
   

   
   

   ​​Summary of Round Trip Latency figures at the work site